Expression of AtMed15 of Arabidopsis in yeast causes flocculation and increases ethanol production in yeast culture.

Pradeep Dahiya,Divya S Bhat,Jitendra K Thakur

doi:10.1038/srep27967

Pradeep Dahiya, Divya S Bhat + Show 1 more

Open Access

https://doi.org/10.1038/srep27967

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Abstract

Mediator, a multiprotein complex involved in transcription of class II genes, was first discovered in yeast and then characterized in many metazoans revealing a striking structural conservation of the complex. However, sequences of Mediator subunits are not well conserved raising a question on the functional conservation of these individual subunits. In this study, expression of Med15 of Arabidopsis (AtMed15) in gal11∆ yeast could not complement the function of ScGal11 in galactose metabolism and resistance against cycloheximide. Surprisingly, AtMed15 changed the morphology of the yeast cells. The cells adhered strongly on the surface of the agar media, and showed robust flocculation in the liquid media without affecting the growth. The AtMed15-induced adhesion and flocculation were observed in different carbon sources. Calcium-assisted cell wall-bound mannan-binding proteins were found to be involved in this flocculation, which was unaffected by wide fluctuation of pH or temperatures revealing its constitutive robust nature. Expression of few flocculation related Flo genes was up-regulated in these cells. Interestingly, there was significant increase in ethanol production by the yeast expressing AtMed15. Robust and constitutive flocculation and increased ethanol production by yeast cells harbouring AtMed15 indicate an opportunity of its important usage in biotechnology industries.

Highlights

Mediator, a multiprotein complex involved in transcription of class II genes, was first discovered in yeast and characterized in many metazoans revealing a striking structural conservation of the complex
Expression of Med[15] of Arabidopsis (AtMed15) in gal11∆ yeast could not complement the function of ScGal[11] in galactose metabolism and resistance against cycloheximide
In order to understand the mechanism of flocculation induced by AtMed[15], we studied expression of flocculin and adhesion related genes in yeast cells harbouring AtMed[15] cDNA or just the vector as a control by microarray analysis and Real-Time PCR (Fig. 5a,b)

Summary

Introduction

A multiprotein complex involved in transcription of class II genes, was first discovered in yeast and characterized in many metazoans revealing a striking structural conservation of the complex. These reports suggest that in eukaryotes ranging from simple unicellular yeasts to complex multicellular insects and mammals, Med[15] is a node for diverse pathways relevant to processes like lipid metabolism, sugar metabolism and xenobiotic detoxification In all these reports, Med[15] has been shown to be targeted by the specific transcription factors to recruit transcriptional machinery at the cognate promoter to initiate the transcription process. Expression of Arabidopsis Med[15] cDNA (AtMed15) in Saccharomyces cerevisiae could not complement the function of Gal[11] in yeast for drug resistance and galactose metabolism, but drastically changed the morphology of the cells. There was significant increase in ethanol production by these yeast cells providing an important scope of possible biotechnological applications

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